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Biomedical subjects

J L Walker

Publications and source records attributed to J L Walker.

At least 91 records · Page 5Linked to original sources
PubMed1990

The influence of endometriosis on the staging of cervical cancer.

Pelvic endometriosis often presents as nodularity of the uterosacral and broad ligaments. Therefore, the presence of unrecognized pelvic endometriosis in cervical cancer patients can masquerade as parametrial spread of tumor, preventing correct assessment of stage of disease. A review of three cases in which these disease processes coexisted demonstrates that endometriosis can easily be mistaken for tumor extension on pelvic examination, computed tomography, and even gross inspection at laparotomy, resulting in incorrect staging and inappropriate management decisions. Because clinical staging often is inaccurate in cervical cancer patients with a history of endometriosis, pre-treatment operative assessment should be considered and frozen sections are recommended to assist with intraoperative management whenever the diagnosis of endometriosis could be entertained.

Adenocarcinoma↗
PubMed1990

Management of endometrial cancer with suspected cervical involvement.

The 1989 International Federation of Gynecology and Obstetrics (FIGO) staging system for endometrial cancer cells for operative assessment of the extent of uterine disease, grade, and sites of metastasis before assigning a stage to the cancer. In the current study, 70 endometrial cancer patients with suspected cervical involvement based on a positive endocervical curettage or punch biopsy were treated with initial surgery followed by tailored radiation or chemotherapy. Only 37% of the patients had operative findings consistent with the preoperative suspicion of stage II disease. Postoperative therapy was determined by the extent of cervical involvement, depth of myometrial invasion, cell type, tumor grade, and the presence and location of extra-uterine disease. Based upon these parameters, 21 patients were believed to have low risk for pelvic recurrence and received no adjuvant therapy (90% 5-year survival); 38 patients received postoperative pelvic radiation because of high-risk factors for pelvic recurrence or pelvic nodal involvement (65% 5-year survival); and 11 patients received chemotherapy and/or extended radiation because of extrapelvic disease (no 5-year survivors). The approach outlined supports initial surgery for cases of endometrial cancer with suspected cervical involvement. This approach permits accurate surgical staging under the new FIGO system, avoids radiotherapy in many patients whose disease is less extensive than suspected preoperatively, and can accomplish good local control with limited morbidity.

Combined Modality Therapy↗
PubMed1990

Cellular fibroma masquerading as ovarian carcinoma.

The presence of a benign pelvic mass, ascites, and an elevated CA 125 tumor marker level may mimic the presentation of ovarian adenocarcinoma. Two cases of ovarian cellular fibromas are reported to illustrate that the presence of ascites in association with an elevated CA 125 serum level may mislead physicians into a diagnosis of ovarian carcinoma. Although CA 125 is helpful for following patients after ovarian carcinoma has been diagnosed histologically, it has limited value as a screening test. Exploratory laparotomy with excision of the pelvic mass remains the only reliable and acceptable method available to achieve an accurate diagnosis.

Adenocarcinoma↗
PubMed1989

Personality characteristics of the mothers of children with disruptive behavior disorders.

The biological mothers of 100 outpatient children aged 6-13 years completed the Minnesota Multiphasic Personality Inventory (MMPI). Mothers of children given DSM-III diagnoses of conduct disorder (CD; n = 13) had significantly higher scores on MMPI scales associated with antisocial behavior (Pd and Ma), histrionic behavior (Hs and Hy), and disturbed adjustment (Sc). In contrast, the children's diagnosis of attention deficit disorder with hyperactivity (ADD/H; n = 22) was not significantly associated with any maternal MMPI elevations, and the CD x ADD/H interactions were not significant for any MMPI scale. These results indicate that CD is linked to maternal personality disorder, but ADD/H is not.

Adolescent↗
PubMed1989

Comparative effects of methylphenidate on ADD girls and ADD boys.

The effects of 0.3 mg/kg methylphenidate were compared for 12 ADD boys and 12 ADD girls participating in a summer treatment program for children with behavior and/or learning problems. Previous investigations have suggested that ADD girls may differ from ADD boys in some important respects. No information exists regarding whether the effects of the most common treatment for these children, methylphenidate, has comparable effects on boys and girls. The boys and girls were matched for age and IQ. The results revealed equivalent and beneficial effects of methylphenidate for both boys and girls. Methylphenidate therefore would appear to be as useful a treatment for ADD girls as for ADD boys.

Attention Deficit Disorder with Hyperactivity↗
PubMed1989

Purification and preliminary characterization of sucrose-phosphate synthase using monoclonal antibodies.

Monoclonal antibodies specific for sucrose phosphate synthase (SPS; EC 2.4.1.14) have been obtained for the first time. Three independent clones have been isolated which inhibited spinach (Spinacia oleracea L.) leaf SPS activity and facilitated the enzyme purification by immunoprecipitation. All three clones were specific for the spinach enzyme but neither inhibited nor precipitated the SPS present in tissue extracts of maize (Zea mays L.), barley (Hordeum vulgare L.), soybean (Glycine max L.), and sugar beet (Beta vulgaris L.). The inhibition of SPS activity by all three clones was reversible in the presence of UDPG, suggesting the presence of an epitope at the substrate-binding site. Immunoprecipitates of active enzyme preparations consistently revealed the presence of a 120 kilodalton polypeptide, indicating that the enzyme may be a homotetramer with a native molecular weight of about 480 kilodaltons. The occasional appearance of a 52 kilodalton polypeptide in the immunoprecipitates of some enzyme preparations was not the result of proteolysis, was not necessary for enzyme activity, and did not contain an antigenic site as revealed by Western blotting experiments. All three antibodies bind weakly to the SDS denatured 120 kilodalton subunit bound to nitrocellulose. The specific activity of the purified spinach enzyme was determined for the first time to be approximately 150 units per milligram SPS protein (pH 7.5 and 25 degrees C) based on quantitative immunoprecipitation of the enzyme.

Journal Article↗
PubMed1988

Self-reported stress symptoms in farmers.

The self-reported incidence of stress-related symptoms was studied in 817 farm men and women and 109 urban residents. Close to 50% of the farm sample reported the frequent to constant occurrence of the symptoms of trouble relaxing, loss of temper, and fatigue. Over 30% of the farmers reported similar occurrence rates for six additional symptoms. Self-reported symptom rates were significantly higher in farm women than in farm men, higher in younger farmers, higher in mixed farming operations, and higher in farmers who were holding off-farm employment. Symptom scores were significantly higher in the farmers compared to the urban sample. A stepwise discriminant analysis showed that scores on five symptoms were able to distinguish meaningfully between farm and urban groups. It was suggested that the chronic stress associated with the current farm financial crisis may be causing a high self-reported incidence of symptoms among farmers.

Adult↗
PubMed1988

Fractures of the body of the trapezium.

Fractures of the body of the trapezium are uncommon. Ten such cases are reported. They may be associated with other carpal or metacarpal fractures and may require special radiographic views for diagnosis. There does not appear to be a consistent mechanism of injury. A classification system is proposed based on the five fracture configurations identified. Open reduction with internal fixation of the displaced articular surface is preferred.

Adolescent↗
PubMed1988

Centrifugation of antibiotic impregnated bone cement.

Centrifugation is used to increase the strength of bone cement in total joint arthroplasty. Antibiotics have been incorporated into cement for the treatment and prophylaxis of infection. To determine the effect of centrifugation on antibiotic containing cement, tobramycin and cefamandole impregnated Surgical Simplex P polymethylmethacrylate was centrifuged using manufacturers' techniques. The concentration of antibiotics was measured throughout the cement column by a zone of inhibition bioassay. No difference in the distribution of the antibiotics could be demonstrated as compared to hand mixed controls. Centrifugation decreased the number of large air inclusions overall, however, a significant number were noted to remain at the top of the centrifugation gradient. It was concluded that centrifugation of an antibiotic impregnated bone cement, utilizing this technique, may be used without disturbing the antibiotic distribution. Discarding the top 1 cm of liquid centrifuged column to remove residual air inclusions is recommended.

Biological Assay↗
PubMed1987

Isolated muscle cells as a physiological model.

Summary of a symposium presented by the American Physiological Society (Cell and General Physiology Section and Muscle Group) at the 70th Annual Meeting of the Federation of American Societies for Experimental Biology, St. Louis, Missouri, April 15, 1986, chaired by M. Lieberman and F. Fay. This symposium reflects a growing interest in seeking new technologies to study the basic physiological and biophysical properties of cardiac, smooth, and skeletal muscle cells. Recognizing that technical and analytical problems associated with multicellular preparations limit the physiological significance of many experiments, investigators have increasingly focused on efforts to isolate single, functional embryonic, and adult muscle cells. Progress in obtaining physiologically relevant preparations has been both rapid and significant even though problems regarding cell purification and viability are not fully resolved. The symposium draws attention to a broad, though incomplete, range of studies using isolated or cultured muscle cells. Based on the following reports, investigators should be convinced that a variety of experiments can be designed with preparations of isolated cells and those in tissue culture to resolve questions about fundamental physiological properties of muscle cells.

Animals↗
PubMed1986

Renal cell carcinoma in pregnancy.

Renal cell carcinoma is the most common renal neoplasm associated with pregnancy. The most common presenting symptoms are pain and a palpable mass. Although renal neoplasms in pregnancy are rare, the pregnancy demands special consideration in the methods of diagnostic evaluation. The relationship between renal cell carcinoma and pregnancy is unclear. Treatment is usually radical nephrectomy regardless of the stage of pregnancy. Two new cases are presented with a review of the literature.

Adult↗
PubMed1986

Intracellular potassium activity, potassium equilibrium potential and membrane potential of carotid body glomus cells.

The intracellular potassium activity (ai(K)) of glomus cells in isolated rabbit carotid bodies was measured with potassium ion selective microelectrodes (K+ electrodes). The measurements yielded a mean ai(K) value of 33.0 mM in Hepes-buffered Tyrode's solution equilibrated with 100% O2. This value is significantly higher than that predicted by assuming that K+ ions are passively distributed across the membrane of glomus cells. The relationship between the membrane potential (EM) and the equilibrium potential of K+ ions (EK) at various extracellular potassium activities (ao(K] suggests that K+ ions are not involved in the maintenance of the carotid body glomus cell EM.

Animals↗
PubMed1986

Light-induced increases in the glycine decarboxylase multienzyme complex from pea leaf mitochondria.

The rates of mitochondrial glycine oxidation estimated by CO2-release and glycine-bicarbonate exchange activities in fully greened tissues are approximately 10 times greater than those of etiolated pea leaves and potato tuber mitochondria. The release of CO2 from glycine in intact mitochondria isolated from dark-grown and nonphotosynthetic tissues was sensitive to inhibitors of mitochondrial electron transport, glycine transport, and glycine decarboxylase activities. The CO2-release and glycine-bicarbonate exchange activities in crude mitochondrial protein extracts from light-grown versus dark-grown tissues exhibited light/dark ratios of 12 and 21, respectively. This suggests that the differences in capacity to oxidize glycine reside with the glycine decarboxylase enzyme complex itself. The complex is composed of four subunit enzymes, the P, H, T, and L proteins, which can be isolated individually and reconstituted into the active enzyme. The activities of P and T proteins were at least 10 times higher in fully greened pea leaves than in the etiolated tissue, while the H and L protein activities were four times higher in these same tissues. The levels of P and T proteins detected immunochemically were substantially lower in total mitochondrial extracts prepared from leaves of dark-grown pea seedlings. Labeling of whole pea seedlings and in vitro protein synthesis with isolated mitochondria indicated that the entire glycine decarboxylase enzyme complex is cytoplasmically synthesized and therefore encoded by the nucleus. Polypeptides synthesized from total leaf polyadenylated mRNA isolated from leaves of both the dark-grown and light-treated peas indicated the presence of P protein. This implies that translatable messages for this enzyme are present at some level throughout leaf development.

Amino Acid Oxidoreductases↗
PubMed1986

Inhibitory action of furosemide on the active chloride transport of papillary heart muscle in rabbit.

The action of furosemide on the intracellular chloride activity, ai(Cl), of rabbit papillary muscle was investigated with Cl ion selective microelectrodes. With furosemide concentrations greater than 1 microM, ai(Cl) decreased. Furthermore, the decrease in ai(Cl) was larger as the furosemide concentration increased. Lowering the extracellular sodium concentration, [Na]o, by replacing Na with choline, significantly reduced the effect of furosemide on ai(Cl). The results provide evidence that the membrane of rabbit heart cells possess a furosemide sensitive chloride transport mechanism related to [Na]o.

Animals↗
PubMed1986

The intracellular chloride activity of glomus cells in the isolated rabbit carotid body.

The resting membrane potential (EM) and intracellular chloride activity (ai(CI] of glomus cells were measured in isolated rabbit carotid bodies using conventional and chloride-selective microelectrodes. EM and ai(CI) were -25.9 +/- 1.4 mV (mean +/- S.E.M., n = 13) and 20.9 +/- 1.9 mV (mean +/- S.E.M., n = 13), respectively. When the chloride equilibrium potential (ECI) was shifted in a positive direction, EM depolarized. It is concluded that chloride ions are not passively distributed across the glomus cell membrane and that they play an important role in determining EM.

Animals↗
PubMed1986

Glycine decarboxylase multienzyme complex. Purification and partial characterization from pea leaf mitochondria.

The P, H, and T proteins of the glycine cleavage system have been purified separately from pea leaf mitochondria and demonstrate molecular weights of 98,000, 15,500, and 45,000, respectively, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular weight of P protein by gel filtration was 210,000, indicating that this enzyme has a native homodimer conformation. Reconstitution assays containing purified P, H, and T proteins and yeast lipoamide dehydrogenase catalyze the oxidation of glycine and demonstrate a strict dependence on pyridoxal phosphate, tetrahydrofolate, NAD+, and dithiothreitol. The released CO2, methylamine-H protein intermediate, and methylenetetrahydrofolate are produced in stoichiometric amounts from glycine during the cleavage reaction. H protein acts as co-substrate with glycine during the decarboxylation reaction, demonstrating an apparent Km value of 2.2 microM. P and H protein alone jointly catalyze the glycine carboxyl-14 CO2 exchange reaction in the presence of pyridoxal phosphate and dithiothreitol. L protein of the glycine cleavage system was immunopurified using monoclonal antibodies. Antigenic and molecular weight similarities of the L protein with the lipoamide dehydrogenase component of the pyruvate dehydrogenase complex were shown suggesting the possibility of common isomers of lipoamide dehydrogenase for the two enzyme complexes.

Amino Acid Oxidoreductases↗
PubMed1986

Synthesis and quantitative structure-activity relationships of antiallergic 2-hydroxy-N-1H-tetrazol-5-ylbenzamides and N-(2-hydroxyphenyl)-1H-tetrazole-5-carboxamides.

The synthesis and antiallergic activity of a series of 2-hydroxy-N-1H-tetrazol-5-ylbenzamides and isomeric N-(2-hydroxyphenyl)-1H-tetrazole-5-carboxamides is described. A relationship between structure and intravenous antiallergic activity in the rat passive cutaneous anaphylaxis (PCA) test has been established using a Hansch/Free-Wilson model and used to direct studies toward potent derivatives. The contribution of physicochemical properties to activity is discussed. One member of this series, N-(3-acetyl-5-fluoro-2-hydroxyphenyl)-1H-tetrazole-5-carboxamide (3f), which was selected for further evaluation, has an ID50 value of 0.16 mg/kg po and is 130 times more potent than disodium cromoglycate (DSCG) on intravenous administration.

Animals↗